I've been following TheCherno's OpenGL tutorials and I got to the point where I could render a square by using an index buffer. Now I wanted to vary the color of the square by using $$\frac{\sin(t) + 1}{2}$$ as my normalized time-varying function to be used in each of the RGB entries in color. I thought I might proceed as follows: this is my fragment shader.
#shader fragment
#version 330 core
layout(location = 0) out vec4 color;
uniform float time;
float time_Color(float t) {
return (sin(t) + 1) / 2;
}
void main()
{
color = vec4(time_Color(time), time_Color(time - 0.2), time_Color(time - 0.4), 1.0f);
}
in my main loop in main.cpp, I have:
int location = glGetUniformLocation(theProgram, "time");
//Main loop
glfwSetTime(0);
while (!glfwWindowShouldClose(mainWindow)) {
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glUniform1f(location, static_cast<float>(glfwGetTime()));
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr);
glfwSwapBuffers(mainWindow);
glfwWaitEvents();
}
When I run this program, I do see a color-varying square but the change in color becomes slower and slower as the program continues. Initially the change is gradual but then sometime after like 7 secs, I start to get abrupt changes in color that only get updated after a long time. I suspect this is to do with the sin computation in the GPU but I don't actually know since I'm just beginning out. So why is this code working so slowly/inefficiently the longer the program executes?
